Process of producing felted sheets containing bitumen



,bitumen non-adhesive as Patented Sept. 13, 1932 UNITED STATES PATENT OFFICE GIBSON Y'UNGBL'UT, OF DAYTON, KENTUCKY, ASSIGNOR TO THE RICHARDSON COM- PANY, OE LOCKLAND, OHIO, A CORPORATION OF OHIO PROCESS OF PRODUCING FELTEID SHEETS CONTAINING IBITUMEN No Drawing.

out upon the screen with the fibers; and dur-.

ing the drying process, it is melted by the heat employed and caused to coalesce into a film or body which is of a continuity and thickness depending upon the amount of bituminous material which has been used. With suifi cient heat the bituminous material can be made to penetrate more or less into the fibers.

In this way are produced materials which are the equivalent of saturated or semi-saturated sheets.

There are a number of ways of associating heat plastic and generally waterproofing substances (of which bitumen such as asphalt will serve as an example in these specifications) with a fibrous material in a pulp suitable for felting. One way that has been proposed is merely to subdivide bituminous material very finely and incorporate it in paper stock in the beater or in the stuff chests, relying upon the filtering action of thefibers as they are being felted upon the paper machine screen to retain a desired quantity of the bitumen. Another wa is to render the y emulsifying it with colloidal clay, and to mix the emulsified material with a pulp. In co-pending applications, Serial No. 314,551, of Harry G. Fisher, filed October 23, 1928, and Serial No. 316,611, of Earl P. Stevenson and Harry A. Buron, filed November 1, 1928, ways are described and claimed of making a true pulp in which an association between bitumen and fibers exists which is quite diiferent from a mere mechanical admixture; and a necessary feature of-these processes is the formation of a preliminary association between the bitumen and the fibers before the pulping stage. Here fibers and asphalt are mixed in a mixer before the mass formed thereby is transferred to a beating engine.

Application filed June 15 1929.. Serial No. 371,299.

My process is analogous to the processes -described in the two co-pending applications referred to, but it is not characterized by the bringing about of a preliminary association in a mixing machine; and the finished pulp partakes both of the nature of a true bituminous pulp and of a bitumen and fiber suspension.

It is an object of my invention to cheapen and expedite the bringing of bitumen and fibers into association in water suspension in a useful form.

It is an object of my invention to eleminate the use of a preliminary mixing stage in the formation of useful suspensions of fibers and waterproofing substances, which may be handled as a pulp on a screen. I

These and other objects of my invention which will be set forth hereinafter or will be apparent to one skilled in the art upon reading these specifications, I accomplish by that process of which I shall now describe a preferred embodiment.

. It is not ordinarily possible to add any considerable quantity of bitumen which is not I subdivided to an ordinary'paper mill beater in which a beating action is being carried on. It may be possible to add certain quantities of hard bitumen to heavy fibers in a beater, and by raising the beater blades, distribute the so bitumen more or less evenly through the pulp, and still avoid the disastrous gumming up of the beating engine. However, with the blades raised a proper beating action is not being exerted upon the fibers themselves; the beater in such a process is primarily being used as a mixer, and the true beating of the fibers to fit them for felting must have been carried on before the addition of the bitumen. In order to'beat fibers and bitumen together, a preliminary association becomes increasingly necessary as the quantity of the bitumen is raised. In my process I effect this preliminary association in such a way that I can beat the 05 product and fit the fibers for felting while at the same time distributing the bitumen throughout the mass in at least partial association with the fibers, as distinguished from a mere mechanical supension of finely divided matter. To this end I coat a mass of fibrous material, such as pieces of paper, preferably wet with water, with asphalt or other bitumen in comparatively thin layers. I may do 5 this by taking quantities of wet paper and 'dipping them in fluid bitumen, taking them out, draining them and transferring them to a beating engine in which is a quantity of water. Preferably, however, in commercial practice, I provide a conveyor or trough, upon of the sprayed fibrous material to the beater to prevent undue cooling, and the maintenance of the beater water at a somewhat elevated temperature, will facilitate the heating with hard asphalts. With soft varieties, lower temperatures may be used. This is a matter for individual ,cases and is concerned with the quality and quantity of the'bitumen or other heatplastic.

When treating fibrous material with bitumen, I prefer to have the fibrous material wet for the reason that upon immediate transference to the beating engine the wet fibers are more easily handled and work better initially than dry fibers, which must become wetted by the beater water, and also for the ancillary reason that the moisture of the fibers inhibits complete saturation thereof during the dipping or spraying step: But wet fibrous material is not necessary, and in some instances is not preferable, as when I desire to store.

papers-which have been treated with bitumen rather than to transfer them immediately to the beater. Indeed no special method of treating the papers or other fibrous material is necessary. I may, for example, use a web of paper which has been passed through a bath of asphalt so as to be coated but not complete- 1y saturated, or I may use scrap materials of that character. I may even employ in my process a portion of paper or analogous material which has been completely saturated with bitumen; but I do not claim a process merely of beating up or mascerating completely saturated paper or felt webs in a beating engine. In my process it appears essential that a considerable percentage of the bitumen-treated fibrous material be at least unsaturated within, so that the water can get at the fibers directly to the extent of permitting the action in the beater which I shall hereinafter describe.

When hot asphalt contacts with wet fibers, some of the moisture is driven out of the fibrous material and the asphalt or other bitumen contacts and adheres to some fibers and portions of fibers so as to be bonded to phalt contacts with dry fibers under other than completely saturating conditions. Thus,

before beating, there is formed a type of preliminary association which is different from a mere mechanical mixture of bitumen and fibers in that there is between the bitumen and fibers at least in part a coating if not a saturating contact. But it is to be noted that my treatment of fibrous masses with bitumen before transferring them to the heater is never such as will result in a complete elimination of the moisture and a complete saturation of the masses. Further, when the bitumen is sprayed upon fibrous material moving on a conveyor, the underside of the material is not coated with the bitumen, and this lack of coating, facilitates the beating action.

I find it advisable in beating the stock thus formed, to maintain as little. water in the beater as may be necessary to insure a proper beating action; that is to say, I prefer to run my stock heavy, with the beater water at a temperature depending somewhat on the nature andquantity of the bitumen used; hot water in the beater particularly facilitating the action with some bitumens. I prefer to raise the beater blades slightly, at least in the preliminary stages of the beating, but not much beyond what is common in paper practice, nor beyond the point at which a true beating action is being carried out on the fibers themselves.

I may, if desired, add to the beater untreated fibers in addition to those treated with bitumen. I

It is characteristic of the pulp formed by my process what while it contains a considerable percentage of free bitumen in minute subdivision it also contains a considerable percentage of bitumen in true association withthe fibers, and there may be some fibers or fibrous masses which are entirely coated therewith. A considerable percentage of the bitumen will be found actually adheringto the fibers in a form ranging from interspaced specks to a more or less complete surface film. The association is modified, of course, by the condition of the binder and is facilitated when the binder is soft. The binder condition in turn may be modified by the tem perature in the beater and in this way it is possible to control the condition of the final product and to produce a product on the one hand in which the binder, worked While it is of bitumen will be found in the back Water;

in the former condition many of the finer particles tend to wash out in the back water.

.The pulp formed'in the practice of my invention, as heretofore indicated, may becharacterized as a combination of bituminous suspension, fiber suspension and a suspension of pulped fibers with physically adherent bitumen. It may be felted upon a screen and handled in the same way as ordinary pulp is handled. Under the action of the heat of drying cylinders the bitumen will coalesce and bind the entire mass together, saturating it more or less according to its quantity and quality. By the term bitumen I intend to include heat plastic water-repellant substances, asphalts, pitches, tars, blown oils, waxes, and the like.

Having thus described my invention, what I claim as new and desire to secure by Letters Patent, is

1. That process of forming a feltable mass of fibers and heat plastic waterproofing substance, which comprises associating fibrous aggregates with thin superficial layers of said heat plastic substance, transferring said coated aggregates to a beater and beating them to a pulp.

2.That process of producing a pulp of bitumen and fibrous materials which comprises coating fibrous aggregates with superficial layers of bituminous substance, transferring said aggregates to a beater and beatin g them. I

3. That process of producing a pulp of bitumen and fibrous materials which comprises coating fibrous aggregates with superficial layers of bituminous substance, transferring said aggregates to a beater and beating them, the association of said bitumen and said fibrous aggregates at least in part not being a saturating association.

4. That process of producing a feltable pulp from fibers and bitumen which comprises coating fibrous aggregates with bitumen without mixing, transferring said coated aggregates to a beater and beating said aggregates into a pulp.

5. That process of producing a feltable pulp from fibers and bitumen which com prises coating fibrous aggregates with bitumen without mixing, transferring said coated aggregates to a beater and beating said aggregates into a pulp, the contacting of said bitumen with said aggregates at least in part not being a saturating contact.

6. That process of producing a feltable pulp of fibers and bitumen which comprises associating unmixed aggregates of fibers and bitumen and beating said aggregates without substantially saturating said fibers.

7 That process of producing a feltable pulp from fibers and bitumen which comprises wetting fibrous aggregates and associating said wetted aggregates with bitumen without mixing and saturating. them, and

beating said aggregates.

8. That process of producing a pulp of bitumen and fibers, which comprises working pre-associated bitumen and fibrous aggregates together in the presence of water by beating, the fibers not being saturated with said bitumen, and the quantity of fibrous material being'such in relation to the bitumen that the beating mechanism is protected from the sticking action of said bitumen.

9. That process of producing a feltable pulp of fibers and bitumen which comprises beating pre-associated fibrous aggregates and bitumen together in the presence of water, the bitumen at the start of said beating operation being in thin layers, and a portion thereof in coating contact with a portion of said fibers, the percentage of free fibers being such that the beating mechanism is protected from the action of large quantities of free bitumen.

10. That process of producing a feltable pulp of bitumen and fibers which comprises spraying wetted fibrousaggregates with bitumen without completely coating them, and transferring said fibrous aggregates to a beater and beating them into a pulp.

11. That process of producing a feltable pulp of bitumen and fibers which comprises spraying wetted fibrous aggregates with bitumen without completely coating them and transferring said fibrous aggregates to a beater and beating them into a pulp, and adding during said beating operation untreated fibrous aggregates.

12. That process of producing a feltable pulp of fibers and bitumen which comprises coating fibrous masses with bitumen during continuous movement thereof and transferring said coated masses to a heater and heating them into a pulp.

13. That process of producing a feltable pulp of fibers and bitumen which comprises moving wetted papers beneath a spray of hot bitumen and transferrin the sprayed papers to a beater and beating t em into a pulp.

14. That process of producing va feltable pulp of fibers and bitumen which comprises adding bitumen in thin layers to wetted fibrous material and without any preliminary mixing, beating the composite material thus formed in a beating engine into a pulp suitable for formation on a paper machine screen.

15. That process of producing a fcltable pulp of fibers and bitumen which comprises eating fibrousaggregates which are in partial coatifgbut not substantially in saturating contact with films of asphalt.

GIBSON YUNGBLUT. 

